52bf64c787
Obtained from: Whistle Communications tree Add an option to the way UFS works dependent on the SUID bit of directories This changes makes things a whole lot simpler on systems running as fileservers for PCs and MACS. to enable the new code you must 1/ enable option SUIDDIR on the kernel. 2/ mount the filesystem with option suiddir. hopefully this makes it difficult enough for people to do this accidentally. see the new chmod(2) man page for detailed info.
307 lines
7.8 KiB
Groff
307 lines
7.8 KiB
Groff
.\" Copyright (c) 1989, 1990, 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the Institute of Electrical and Electronics Engineers, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)chmod.1 8.4 (Berkeley) 3/31/94
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.\" $Id: chmod.1,v 1.7 1997/02/22 14:01:29 peter Exp $
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.\"
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.Dd March 31, 1994
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.Dt CHMOD 1
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.Os
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.Sh NAME
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.Nm chmod
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.Nd change file modes
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.Sh SYNOPSIS
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.Nm chmod
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.Oo
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.Fl R
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.Op Fl H | Fl L | Fl P
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.Oc
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.Ar mode
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.Ar file ...
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.Sh DESCRIPTION
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The
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.Nm chmod
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utility modifies the file mode bits of the listed files
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as specified by the
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.Ar mode
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operand.
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl H
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If the
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.Fl R
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option is specified, symbolic links on the command line are followed.
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(Symbolic links encountered in the tree traversal are not followed.)
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.It Fl L
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If the
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.Fl R
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option is specified, all symbolic links are followed.
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.It Fl P
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If the
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.Fl R
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option is specified, no symbolic links are followed.
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.It Fl R
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Change the modes of the file hierarchies rooted in the files
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instead of just the files themselves.
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.El
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.Pp
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Symbolic links do not have modes, so unless the
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.Fl H
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or
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.Fl L
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option is set,
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.Nm chmod
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on a symbolic link always succeeds and has no effect.
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The
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.Fl H ,
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.Fl L
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and
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.Fl P
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options are ignored unless the
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.Fl R
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option is specified.
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In addition, these options override each other and the
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command's actions are determined by the last one specified.
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.Pp
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Only the owner of a file or the super-user is permitted to change
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the mode of a file.
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.Pp
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The
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.Nm chmod
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utility exits 0 on success, and >0 if an error occurs.
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.Sh MODES
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Modes may be absolute or symbolic.
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An absolute mode is an octal number constructed by
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.Ar or-ing
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the following values:
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.Pp
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.Bl -tag -width 6n -compact -offset indent
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.It Li 4000
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set-user-ID-on-execution
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( see
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.Xr chmod 2
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for directories )
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.It Li 2000
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set-group-ID-on-execution
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.It Li 1000
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sticky bit, see
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.Xr chmod 2
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.It Li 0400
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read by owner
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.It Li 0200
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write by owner
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.It Li 0100
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execute (or search for directories) by owner
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.It Li 0070
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read, write, execute/search by group
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.It Li 0007
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read, write, execute/search by others
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.El
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.Pp
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The read, write, and execute/search values for group and others
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are encoded as described for owner.
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.Pp
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The symbolic mode is described by the following grammar:
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.Bd -literal -offset indent
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mode ::= clause [, clause ...]
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clause ::= [who ...] [action ...] last_action
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action ::= op [perm ...]
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last_action ::= op [perm ...]
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who ::= a | u | g | o
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op ::= + | \- | =
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perm ::= r | s | t | w | x | X | u | g | o
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.Ed
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.Pp
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The
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.Ar who
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symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts
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of the mode bits, respectively.
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The
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.Ar who
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symbol ``a'' is equivalent to ``ugo''.
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.Pp
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.ne 1i
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The
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.Ar perm
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symbols represent the portions of the mode bits as follows:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It r
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The read bits.
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.It s
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The set-user-ID-on-execution and set-group-ID-on-execution bits.
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.It t
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The sticky bit.
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.It w
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The write bits.
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.It x
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The execute/search bits.
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.It X
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The execute/search bits if the file is a directory or any of the
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execute/search bits are set in the original (unmodified) mode.
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Operations with the
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.Ar perm
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symbol ``X'' are only meaningful in conjunction with the
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.Ar op
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symbol ``+'', and are ignored in all other cases.
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.It u
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The user permission bits in the mode of the original file.
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.It g
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The group permission bits in the mode of the original file.
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.It o
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The other permission bits in the mode of the original file.
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.El
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.Pp
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The
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.Ar op
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symbols represent the operation performed, as follows:
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.Bl -tag -width 4n
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.It +
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If no value is supplied for
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.Ar perm ,
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the ``+'' operation has no effect.
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If no value is supplied for
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.Ar who ,
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each permission bit specified in
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.Ar perm ,
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for which the corresponding bit in the file mode creation mask
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is clear, is set.
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Otherwise, the mode bits represented by the specified
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.Ar who
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and
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.Ar perm
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values are set.
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.It \&\-
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If no value is supplied for
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.Ar perm ,
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the ``\-'' operation has no effect.
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If no value is supplied for
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.Ar who ,
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each permission bit specified in
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.Ar perm ,
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for which the corresponding bit in the file mode creation mask
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is clear, is cleared.
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Otherwise, the mode bits represented by the specified
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.Ar who
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and
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.Ar perm
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values are cleared.
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.It =
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The mode bits specified by the
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.Ar who
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value are cleared, or, if no who value is specified, the owner, group
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and other mode bits are cleared.
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Then, if no value is supplied for
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.Ar who ,
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each permission bit specified in
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.Ar perm ,
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for which the corresponding bit in the file mode creation mask
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is clear, is set.
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Otherwise, the mode bits represented by the specified
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.Ar who
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and
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.Ar perm
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values are set.
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.El
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.Pp
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Each
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.Ar clause
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specifies one or more operations to be performed on the mode
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bits, and each operation is applied to the mode bits in the
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order specified.
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.Pp
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Operations upon the other permissions only (specified by the symbol
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``o'' by itself), in combination with the
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.Ar perm
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symbols ``s'' or ``t'', are ignored.
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.Sh EXAMPLES
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.Bl -tag -width "u=rwx,go=u-w" -compact
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.It Li 644
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make a file readable by anyone and writable by the owner only.
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.Pp
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.It Li go-w
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deny write permission to group and others.
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.Pp
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.It Li =rw,+X
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set the read and write permissions to the usual defaults, but
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retain any execute permissions that are currently set.
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.Pp
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.It Li +X
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make a directory or file searchable/executable by everyone if it is
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already searchable/executable by anyone.
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.Pp
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.It Li 755
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.It Li u=rwx,go=rx
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.It Li u=rwx,go=u-w
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make a file readable/executable by everyone and writable by the owner only.
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.Pp
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.It Li go=
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clear all mode bits for group and others.
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.Pp
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.It Li g=u-w
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set the group bits equal to the user bits, but clear the group write bit.
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.El
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.Sh BUGS
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There's no
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.Ar perm
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option for the naughty bits.
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.Sh SEE ALSO
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.Xr chflags 1 ,
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.Xr install 1 ,
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.Xr chmod 2 ,
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.Xr stat 2 ,
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.Xr umask 2 ,
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.Xr fts 3 ,
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.Xr setmode 3 ,
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.Xr symlink 7 ,
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.Xr chown 8
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.Sh STANDARDS
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The
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.Nm chmod
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utility is expected to be
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.St -p1003.2
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compatible with the exception of the
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.Ar perm
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symbols
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.Dq t
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and
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.Dq X
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which are not included in that standard.
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.Sh HISTORY
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A
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.Nm
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command appeared in
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.At v1 .
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